Effects of ethylene on plants include:-

Controlling the ripening process in fruits has been a problem for

many years. In recent times techniques such as geneticengineering and post harvest technology had been used to controlthe ripening process.In this study we looked at the respiration rate and ethylenebiosynthesis in bananas (cv giant Cavendish), and how postharvesttechnology can enhance the shelf life of bananas. Ethylenesynthesis in Carica papaya and Artocarpus altilis (breadfruit) wasalso determined during the ripening process.

ACC synthase is inhibited by:-

Controlled atmosphere is most commonly used to

slow the ripening of fruits and to slow the decay of vegetables This can be done by modification of the oxygen/carbon dioxide concentration of the atmosphere Low oxygen concentration (3-4%) slows ripening because it reduces the autocatalytic production of ethylene. 8 Postharvest technology contd

For controlled atmosphere experiments, the use of a

semipermeable membrane was developed by Marcelli and Leteinturier (1966-1967). The membrane is an elastomer of silicone which has the ability to exchange gases at different rates depending on their chemical and physical properties. At 1 atm its permeability to CO2 is 1750 dm3 .day -1.M -2 ; O is 320 dm3. day -1.M-2; ethylene is 700 2 dm3 .day -1.M -2. 9 Postharvest technology contd

13 Silicone Membrane System The use of a silicone membrane that is fitted to a chamber (50 cm x 25 cm i.d.) can be used to modify the composition of the air (3% O2 and 5% CO2) and prevent ethylene - stimulated ripening of Giant Cavendish bananas. Experiments were carried out in a cold room at 15C and terminated after 6 weeks.

Siliconemembrane

Chamber 14 Diffusion Channel System Diffusion channels, installed on laboratory scale chambers, were used to provide and maintain controlled atmosphere (CA) conditions (3% O2 and 5% CO2) to prevent ethylene - stimulated ripening of Giant Cavendish bananas. Experiments were carried out in a cold room at 15C and terminated after 6 weeks.

Results showed that an atmospheric composition of 3.5% CO2 and 3% O2 was most suitable for preserving banana quality. Fruits stored inthis atmosphere remained in an unripe state for 6 weeks and were of superior quality to controls and fruits stored in different CO 2/ O2 atmospheres.Fruit stored at RA were fully ripe after 29 days.

23 Thiabendazole Treatment

Figure7. Bananas treated with Figure 8. Bananas that were not

thiabendazole (100 ppm) treated with thiabendazolebefore storage at CA before storage at CA.

24 Discussion1. The primary benefit of the CA/MA storage system is that the fruit will maintain its freshness and quality for a longer period of time than it would if stored under regular atmosphere. Hence more foreign exchange can be earned due to less spoilage. Indeed this technique can be a good alternative to genetically engineered fruits, taking into account the ever growing resistance to genetically engineered products in the UK.

2. There is also considerable use of chemicals in postharvest storage, particularly to protect the fruit from insects, bacterial and fungal pathogens and to reduce or inhibit ripening. The widespread use of these chemicals should be restricted, due to cost and health implications.

3. The main objective was achieved. The shelf-life of the fruit was enhanced, while maintaining optimum quality of the fruit. Ethylene production was implicated in the ripening process of fruits.

4. The techniques used for enhancing the shelf-life of bananas were successful:- a) silicone membrane, which is differentially permeable to gases. b) the diffusion channel system which is based on the principle of diffusion of gases through channels 25 Future work1. To apply the technology toother fruits such as naseberry, mangoes, starapples etc.2. To scale-up the chambers tostore larger quantity of fruits.